// Copyright 2011 Google Inc. All Rights Reserved.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Author: tpw@google.com (Tamsyn Waterhouse)

#include "config.h"
using namespace std;
#include "math/quaternion.h"

namespace energy_rec {

// QuaternionMultiply
//   Multiplies this by other, storing the result in this.
void Quaternion::QuaternionMultiply(const Quaternion &other) {
  const FloatType *a = Get(kCartesian);
  const FloatType *b = other.Get(kCartesian);
  const FloatType result[4] = {
    a[0] * b[0] - a[1] * b[1] - a[2] * b[2] - a[3] * b[3],
    a[0] * b[1] + a[1] * b[0] + a[2] * b[3] - a[3] * b[2],
    a[0] * b[2] - a[1] * b[3] + a[2] * b[0] + a[3] * b[1],
    a[0] * b[3] + a[1] * b[2] - a[2] * b[1] + a[3] * b[0]
  };
  Set(kCartesian, result);
}

}  // namespace energy_rec
